The penance horn can be obtained for free from Commander Connad at the Barbarian Assault minigame (no Barbarian Assault points are required to acquire the horn which comes uncharged). The item gives bonus experience to Agility, Mining and Firemaking, charging while playing the minigame. Bonus experience can then be claimed by checking the horn, then selecting a skill.

To begin charging the horn, the player should enter any waiting room and rotate the statue located in the northern part of the room. After rotating, the horn will gain charges as the player plays the minigame, but no honour points will be earned. Thus, the player cannot charge the horn and gain honour points at the same time. The horn does not need to be taken in to the minigame to obtain charges.

If the player dies with the horn, Commander Connad will give it back for free and with the same amount of charges it had before it was lost.

11 cycles and 7 extra waves are needed to charge the horn fully if a player does waves 1-10. However, some players prefer to do waves 1-5, which fills the horn after 36 cycles.

The completion of any wave fills your horn by exp based on the point total for that round, averaging around 100 waves, or 10 rounds of all 10 waves, for a full horn. It's widely debated whether doing the entire 10 waves ten times is faster to fill the horn - it's also possible to fill the horn by simply doing wave one 100 times, since the bonus for doing higher waves may or may not apply to obtaining potential. Doing waves 1-5 is recommended if using this method.

As of 11/04/2012 the horn has been updated to display a percentage of potential. Please submit data on the talk page.